A lithographic apparatus is a machine that applies a desired pattern onto a target portion of a substrate. Lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that circumstance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern corresponding to an individual layer of the IC, and this pattern can be imaged onto a target portion (e.g. including part of, one or several dies) on a substrate (e.g. a silicon wafer) that has a layer of radiation-sensitive material (resist). In general, a single substrate will contain a network of adjacent target portions that are successively exposed. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion in one go, and so-called scanners, in which each target portion is irradiated by scanning the pattern through the beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction.
U.S. Pat. No. 6,737,662 describes a lithographic apparatus in which an array of mirrors is used to apply a desired angular intensity distribution to a beam of radiation, the beam of radiation subsequently being used to project a pattern onto a target portion of a substrate.
It is desirable, for example, to provide a lithographic apparatus which overcomes or mitigates one or more shortcomings of the apparatus described in U.S. Pat. No. 6,737,662.